The answer to this question is an unambiguous “yes”. It is not possible, it is true, to have a currency crisis inside a currency union, provided the currency union is credible, though currency risk returns, implicitly, as soon as it is not. But balance-of-payments and currency crises are NOT the same thing. A balance-of-payments crisis can show itself in a currency union in one (or, more likely, both) of two ways: as a credit crisis or as a regional economic slump.
The fundamental point was made by the British economist, Tony Thirlwall, in a column entitled “Emu is no cure for problems with the balance of payments”, in the Financial Times of October 9 1991. In this he was responding to the then widespread argument that “we don’t talk about the balance of payments difficulties of Scotland, Wales and the North of England, or of Sicily and Apulia. But this does not mean that they don’t exist.”